Recently, electronic circuit boards, which are obtained by forming electronic circuit patterns on insulating substrates, such as electronic circuit boards, plastic substrates (including films), ceramic substrates, or insulated substrate in which metal substrates or the like are coated with plastic or the like, have been developed. Further, accompanying this, device for forming electronic circuits using solder bonding of electronic components, such as IC devices, semiconductor chips, resistors, and capacitors, or the like on such circuit patterns have been widely adopted.
In the case of forming electronic circuits through such device, it is necessary to bond lead terminals of the electronic components to predetermined conductive circuit electrode surface portions of the circuit pattern in advance. As a general method thereof, a technique of printing solder paste or flux after forming a solder thin layer on the conductive circuit electrode surface of the electronic circuit board in advance has been known. Thereafter, by performing mount-positioning and reflow of predetermined electronic components, the lead terminals are solder bonded to the conductive circuit electrode surface portion.
Recently, with the miniaturization of electronic products, there has been a demand for fine pitching of an electronic circuit. For example, as fine pitch components in a small area, a QFP (Quad Flat Package) type LSI having a pitch of 0.3 mm, a CSP (Chip Size Package), an FC (Flip Chip) having a pitch of 0.15 mm, and the like, have been mounted. Because of this, the electronic circuit board requires a fine solder circuit pattern that can handle the fine pitch.
In the related art, as methods for forming a solder circuit composed of a solder film on an electronic circuit board, for example, a plating method, a HAL (Hot Air Leveler) method, a reflow method after printing solder powder paste, and the like, have been known. However, the method for manufacturing a solder circuit using plating makes it difficult to form the solder layer with a necessary thickness. Further, it is difficult to correspond to the fine pitch pattern with the method for printing a solder circuit using plating.
As a method for forming a solder circuit that can correspond to the fine pitch pattern corresponding to these related art methods, the use of a tackifier compound has been known (Patent Document 1). That is, by making the tackifier compounds react on the electronic circuit board, adhesion is imparted on the conductive circuit electrode surface. Through this, it is possible to adhere the solder powder to the conductive circuit electrode surface only. Thereafter, a fine solder circuit can be formed through heating of the electronic circuit board. According to this method, the fine solder circuit can be formed without the need for cumbersome operations such as alignment of the circuit pattern.
As a method for using the tackifier compound, a method in which the solder powder and the electronic circuit board are put inside a tank that is provided with a rotation and vibration device and rotated has been known.
According to this method, a method in which by rotating the tank through a rotating shaft placed in a center portion of the tank, the electronic circuit board is buried in the solder powder. Further, by making the rotating shaft of the tank substantially parallel to the electronic circuit board surface, the solder powder flows between electronic circuit boards, and thus respective electronic circuit boards are completely buried. Thereafter, by vibrating the tank through the rotating shaft, the solder powder is adhered to an adhesive portion of the electronic circuit board (Patent Document 2).
In addition, other than this method, a method for adhering solder powder to the adhesive portion through putting the electronic circuit board and the solder powder or solder suspension in a container and tilting the container has been known. In this method, the electronic circuit board is installed so that the electronic circuit board is parallel to the direction in which the solder powder or the solder suspension flows and the container is vibrated during tilting. Through this, the solder powder is adhered to the adhesive portion of the electronic circuit board (Patent Document 3).
Further, there has also been known a method for immersing the electronic circuit board in vibratable liquid after adhering the solder powder to the adhesive portion of the electronic circuit board (Patent Document 4). Through this, the solder powder that has been adhered to unnecessary positions can be removed. Because of this, it is possible to prevent a short circuit between adjacent circuit patterns.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 7-007244    [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2003-332375    [Patent Document 3] Japanese Unexamined Patent Application Publication No. 2006-278650    [Patent Document 4] Japanese Unexamined Patent Application Publication No. 2007-149818